Theoretical analysis of the atmospheric entry of sub-mm meteoroids of MgxCa1−xCO3 composition
G. Micca Longo, S. Longo
Icarus
Available online 9 December 2017
“Highlights
• This paper is the first study of the atmospheric entry of grains made of mixed carbonatic composition.
• Such compositions have never been considered in previous studies while they are gaining visibility as mineral phases associated to organic matter in Space.
• The study shows that carbonates undergo total conversion to oxides at high altitude for most entry conditions but some carbonate survives for grazing scenarios.
• These results are important in the context of organic matter delivery from Space to Earth.
“Current models allow to reliably simulate mechanical and thermal phenomena associated with a micrometeor passage through the Earth’s atmosphere. However, these models have rarely been applied to materials other than those most common in meteorites, such as silicates and metals. A particular case that deserves attention is the one of micrograins made of minerals, in particular carbonates, which have been associated, in meteorites, with organic molecules. Carbonates are known for their decomposition in vacuum at moderate temperatures, and they might contribute to the thermal protection of organic matter. In this work, a model with non isothermal atmosphere, power balance, evaporation, ablation, radiation losses and stoichiometry, is proposed. This paper includes the very first calculations for meteoroids with a mixed carbonate composition. Results show that the carbonate fraction of these objects always go to zero at high altitudes except for grazing entries, where the reached temperature is lower and some carbonate remains unreacted. For all entry conditions, peculiar temperature curves are obtained due to the decomposition process. Furthermore, a significant impact of decomposition cooling on the temperature peak is observed for some grazing entry cases. Although specific solutions used in these calculations can be improved, this work sets a definite model and a basis for future research on sub-mm grains of relatively volatile minerals entering the Earth’s atmosphere.”
